0.51 Dyneema Composite Fabric vapor barrier socks
0.3oz for the pair. These are very basic, but work very well. Can be worn under a sock or in place of socks. They are intended to be baggy since DCF does not stretch. The material is thin enough that they don't feel bulky when bunched up. Totally impermeable fabric that is very strong. Won't blow out like the ol' bread bags. They will eventually wear out from abrasion, but will last much longer than any plastic bag. Heavier and more durable DCF weights are available upon request.
The seams do not come sealed. If using these as a VBL sock, they generally don't need sealing. The seams mostly get folded over and covered. If you plan to use these as more of a waterproof sock, then the seams can be easily sealed up with tape, or a couple passes of seam sealer.